Travelling trolley assemblies of hoisting appliances run along rails, which are often formed by I-sections. The dimensions of these parts are standardised.
The size of the cross-sectional dimensions of the I-section depends on the maximum carrying force and the width spanned. I-sections of different widths are used even where hoisting appliances with identical carrying forces are used. Since the bottom flange of the I-section passes through the trolley assembly, the distance between the two frame halves varies in accordance with the width of the bottom flange of the section in question.
In order to be able to adjust the travelling trolley assembly to I-sections of different widths, it is known, for example from DE 34 18 800 C1, to couple together the two wheel carriers which essentially form the trolley assembly by means of a cylindrical connecting column. For this purpose, each of the wheel carriers contains a cylindrical bore which is parallel to the axis of rotation of the running wheels. The connecting column in question passes through this bore. In this way, it is possible to adjust the width continuously as desired by displacing the wheel carriers on the connecting column.
In order to secure the wheel carriers axially with respect to the connecting column, so that they cannot move apart from one another, transverse bores are present in each of the wheel carriers, which bores intersect the receiving bore for the connecting column and run at right angles to this bore. In the transverse bore there is a wedge which is provided with cutting ribs and is secured by a pressure screw. When the pressure screw is tightened, the ribs of the wedge cut into the circumferential surface of the connecting column and thus fix the wheel carrier in question on the connecting column.
When the wedge cuts into the connecting column, material is in principle thrown up from this column so as to project beyond the outer circumference. This projecting material represents a considerable obstacle to disassembly if it is intended, for the purpose of removing the travelling trolley assembly from the running rail, to pull the wheel carriers apart along the connecting column. The material which has been thrown up becomes jammed in the receiving bore for the connecting column.
In another embodiment of a travelling trolley for hoisting appliances with accordance with DE-U 83 36 301, the two wheel carriers are connected to one another via at least one threaded rod and a cylinder pin. The cylinder pin is provided at both its ends with threaded studs which are of smaller diameter and pass through corresponding bores in the wheel carriers. The width of the trolley assembly is adjusted by inserting a greater or smaller number of shims between the wheel carrier and the shoulder at which the cylinder pin becomes the threaded stud in question. This design therefore does not provide a description of a continuous adjustment of the width of the trolley assembly. Furthermore, assembly is not always easy.
The threaded pin is situated between the cylinder pin and the travelling assembly rail. The torque stemming from the normal forces of the wheels leads to a tensile stress in the threaded rod and a compressive stress in the cylinder pin which is of significant larger diameter. However, these conditions are only accurately present if the correct width has been set with the aid of lock nuts on the threaded rod. This requires a corresponding level of care which cannot always be guaranteed at the assembly site. However, if the setting tolerances are not precisely observed, the calculated load values do not correspond to the actual load values.
In a solution for a travelling trolley assembly which is known from DE-30 42 225 C2, the connecting column is provided on the outside with a screw thread. One of the two wheel carriers contains a rigidly attached threaded nut for accommodating the connecting column, which is screwed through this nut. That end of the connecting column which is adjacent to the other wheel carrier is cylindrical and smooth and is fitted into a corresponding cylindrical receiving opening. With the aid of a transverse pin which passes through the receiving opening and the connecting column, the connecting column is prevented from rotating about its axis and from sliding out of the receiving device in question.
By rotating the connecting column, the two wheel carriers are screwed towards one another or moved away from one another.
The manufacturing costs for this solution are high. It is not readily possible to provide the connecting column with a suitable threaded profile which runs with a narrow tolerance in the threaded nut of the one wheel carrier. At any rate, the connecting column has to absorb considerable flexural forces which arise because the running wheels, under load and when interacting with the bottom flange of the rails, seek to move the two wheel carriers apart.
In this case, the spline-like grooves which are formed by the screw thread undercuts increase the risk of fatigue cracking of the connecting column as a result of the notch effect emanating from the grooves.
In another embodiment of a travelling trolley for hoisting appliances in accordance with DE-U 83 36 301, the two wheel carriers are connected to one another via at least one threaded rod and a cylinder pin. The cylinder pin is provided at both its ends with threaded studs which are of smaller diameter and pass through corresponding bores in the wheel carriers. The width of the trolley assembly is adjusted by inserting a greater or smaller number of shims between the wheel carrier and the shoulder at which the cylinder pin becomes the threaded stud in question. A continuous adjustment of the width of the trolley assembly is therefore impossible. Furthermore, assembly is complicated.
The threaded pin is situated between the cylinder pin and the travelling assembly rail. The torque stemming from the normal forces of the wheels leads to a tensile stress in the threaded rod and a compressive stress in the cylinder pin which is of significant larger diameter. However, these conditions are only accurately present if the correct width has been set with the aid of lock nuts on the threaded rod. This requires a very high level of care which cannot always be guaranteed at the assembly site. However, if the setting tolerances are not precisely observed, the calculated load values do not correspond to the actual load values.
On the basis of the above considerations, the object of the invention is to provide a travelling trolley assembly of adjustable width which is easy to mount and disassemble.
This object is achieved according to the invention by means of the travelling trolley assembly having the features of claim 1.
Since in the novel travelling trolley assembly threaded rods are used to lock the side frame bars on the connecting column, it is possible to use a smooth cylindrical connecting column which is not damaged even when used to lock the side frame bars. Any dismantling operation which may be required is correspondingly easy. Furthermore, it is possible to use side frame bar designs in which there is no space which would easily allow transverse wedges to be accommodated for fixing purposes. For example, in the case of box-shaped designs for the side frame bars, there would be no possibility of using wedges such as those which are known from the prior art for locking purposes. By contrast, the use of a threaded rod for the continuous adjustment as desired to the distance between the two side frame bars is readily possible.
The manufacturing cost of the side frame bars is reduced if these are of identical design or at least are mirror images of each other.
In order to allow the side frame bar to be adjusted easily on the connecting column in question, the side frame bar contains a suitable sliding-guidance device. In the most simple case, this sliding-guidance device comprises two openings which are aligned with one another, are spaced apart from one another, are coaxial with respect to one another and are formed in walls of the frame unit. This embodiment favours box-like sections for producing the frame units. It is possible to make use of the considerable advantages of box-like sections, which consist in the fact that they are significantly lighter than solid structural components of the same load-bearing capacity.
In order to facilitate assembly, it is advantageous if one of the two side frame bars is connected to the connecting column in an essentially nondisplaceable manner. The receiving device for the connecting column may in this case be of similar design to the sliding-guidance device, in which case it is merely necessary in addition to provide an axial securing means for the connecting column.
A very simple axial securing means is obtained if the connecting column is provided at one end with a tangential groove which is formed in the transverse direction and in which a platelike securing element which is screwed onto the side frame bar in question engages.
The threaded rod may be a commercially available threaded rod and is advantageously attached to the side frame bars with the aid of locked nuts. For this purpose, each side frame bar contains a corresponding bore as a receiving device for the threaded rod.
If box sections are used for the side frame bar, it is advantageous if the opening through which the threaded rod passes is assigned a further opening, via which a tool for actuating or holding the nut situated in the frame can be introduced.
In order to allow the travelling trolley assembly to move along the running rail under its own power, a traction motor, which is preferably designed as a geared motor, is flanged onto one side frame bar. If it is intended to drive running wheels on both sides of the running rail using the traction motor, the output shaft is preferably designed as a profiled shaft on which there are drive pinions which are longitudinally displaceable but rotationally fixed. The drive pinions mesh with gearwheels which are rotationally fixed to the running wheels in question. Owing to the fact that the pinions can be displaced along the transmission output shaft, the desired width adjustability of the travelling trolley assembly is not impeded by the pinions on the transmission output shaft.
The width adjustment and assembly are particularly simple if the pinions are mounted in an axially nondisplaceable but routable manner in each of the two side frame bars.